PTPN1 and type 2 diabetes mellitus: PTP1B is considered an interesting drug target for the treatment of type 2 diabetes because it dephosphorylates the insulin receptor (IR) and the insulin receptor substrate 1 (IRS-1), inactivating the downstream pathway of phosphatidylinositol 3-kinase (PI3K)-Akt and preventing the translocation of glucose transporter 4 (GLUT4) [8,9] (Figure 1).